For the following system, use the second equation to make a substitution for y in the first equation.
3x + y = 2
y + 4 = 3x

Question

For the following system, use the second equation to make a substitution for y in the first equation.
3x + y = 2
y + 4 = 3x

jackellyn · Answer

solve for y in the second equation

y = 3x -4

Put that in the first equation
3x + (3x-4) = 2
Simplify
3x + 3x - 4 = 2
6x -4 =2

Can you solve for x?

anonymous · Answer

x=1

jackellyn · Answer

So now you substitute that into any of the equations to find y.

3(1) + y=2

Can you solve for y?

anonymous · Answer

Oh they were just asking for 3x + 3x - 4 = 2

jackellyn · Answer

Well for extra practice and a medal can you tell me what y is?

anonymous · Answer

yes

anonymous · Answer

y=-1? nt so sure

jackellyn · Answer

That is right @Hpbby!

Now to check,you substitute both x and y into either equation.

(-1) + 4 = 3(1)
-1 + 4 = 3
3=3

3(1) + (-1)=2
3 -1 =2
2=2

Hooray! :)

anonymous · Answer

Thanks!! :)